Data transmit method and data transmit apparatus

ABSTRACT

In an arrangement in which a CPU transmits data such as audio data through a 32-bit data bus, a format conversion device and a format conversion program are a are newly prepared. Further, input data having a first bit-width (32 bit width) is converted to output data having a second bit-width (24 bit width) in accordance with a predetermined system so that the efficiency of use of the bus at the time of transmitting data is improved; thus, it becomes possible to reduce a data memory area required for multi-media processes.

BACKGROUND OF THE INVENTION

The present invention relates to a data transmission method and a datatransmission apparatus which carry out data processing through a databus.

In the case when a CPU carries out a data transmission process through a32-bit bus, for example, upon carrying out audio data send/receiveprocesses, when the audio data has a 16-bit width, reading and writingoperations are carried out on higher-order and lower-order half words ina 32-bit register for every two data. When the data has a bit width of18, 20, 24 or the like, reading and writing operations are carried outon a higher-order or lower-order bit in a 32-bit register for each data.

However, in the case of data having the bit width of 18, 20, 24 or thelike, data in the higher-order or lower-order remaining bits (14, 12, 8bit) is nullified. For this reason, the efficiency of use of a data businterface used by the CPU is deteriorated. Moreover, since the CPUcarries out encode/decode processes or the like on audio data, theefficiency of use of a memory for storing audio data is alsodeteriorated.

In the future, the CPU comes to carry out multi-media processes, such asaudio, image and data processings, in portable terminals, digitalcameras and the like. In these cases, one bus is shared by a number ofinterfaces so that it becomes essential to improve the efficiency of useof the bus.

SUMMARY OF THE INVENTION

Therefore, the main objective of the present invention is to improve theefficiency of use of a bus at the time of data transmission, whichbecomes more important in the future, and to reduce a data memory arearequired for a CPU to carry out multi-media processing. These objectivesare not limited to audio data.

These and other objectives, features and advantages of the inventionwill be made clear by the following description.

In order to solve the above-mentioned problems, the present invention isprovided with the following means. Basically, input data having a firstbit width is converted to output data having a second bit width inaccordance with a predetermined system. The following descriptiondiscusses a plurality of constituent means; however, these means may beconstituted by hardware or software, or may be constituted by acombination of hardware and software.

In accordance with a first aspect of the present invention, a datatransmission method of the present invention, which processes datathrough an N-bit bus, is provided with the steps of: converting M-bitformat data to N-bit format data; and transmitting the converted N-bitformat data to a data processing device.

A data transmission apparatus corresponding to this data transmissionmethod, which processes data through an N-bit bus, is provided withmeans which converts M-bit format data to N-bit format data and meanswhich transmits the converted N-bit format data to a data processingdevice.

Here, the N-bit is typically exemplified by 32 bits. The M-bit istypically exemplified by 24 bits, 20 bits and 18 bits. However, thesenumbers of bits are only examples, and other numbers of bits maybe used.The M-bit is smaller than the N-bit. Normally, N is not divided by Mwith zero remainder. The data processing device receives external datainputs and externally outputs data (reproduces).

In the case when data, which is recorded and compressed/expanded in amemory on an M-bit basis, is transmitted to a data processing devicethrough an N-bit bus, prior to the transmission, the M-bit format datais preliminarily format-converted to N-bit format data. The N-bit formatdata that has been format-converted is transmitted to a data processingdevice through an N-bit bus. The data transmitted through the N-bit busis not M-bit format data, but N-bit format data. This method makes itpossible to effectively utilize the N-bit bus to the full extent. Inother words, the efficiency of use of the bus is highly improved.

In accordance with a second aspect of the present invention, a datatransmission method of the present invention, which processes datathrough an N-bit bus, is provided with the steps of: transmitting N-bitformat data from a data processing device; and converting thetransmitted N-bit format data to M-bit format data.

A data transmission apparatus corresponding to this data transmissionmethod, which processes data through an N-bit bus, is provided withmeans which transmits N-bit format data from a data processing device;and means which converts the transmitted N-bit format data to M-bitformat data.

Here, the states of N-bit and M-bit are set in the same manner asdescribed above. These are typically exemplified by N=32 and M=24.

In the case when N-bit format data, transmitted from a data processingdevice through an N-bit bus, is recorded or data-compressed in a mainmemory, the data is preliminarily format-converted to M-bit format data.Then, the M-bit format data that has been format-converted is recordedand data-compressed. The recording and data compressing processes arecarried out on an M-bit basis. Here, upon receiving the data transmittedfrom the data processing device through the N-bit bus, the data is notM-bit format data, but N-bit format data. This method makes it possibleto effectively utilize the N-bit bus to the full extent. In other words,the efficiency of use of the bus is highly improved.

In accordance with a third aspect of the present invention, a datatransmit method of the present invention, which processes data throughan N-bit bus, is provided with the steps of: converting N-bit formatdata to M-bit format data; and writing the M-bit format data that hasbeen converted in a buffer memory.

A data transmission apparatus corresponding to this data transmissionmethod, which processes data through an N-bit bus, is provided withmeans which converts N-bit format data to M-bit format data, and meanswhich writes the M-bit format data that has been converted in a buffermemory.

Here, the states of N-bit and M-bit are set in the same manner asdescribed above. These are typically exemplified by N=32 and M=24.

The data received by the data processing device through the N-bit bus isN-bit format data. However, upon externally outputting (reproducing) thedata, the data processing device carries out parallel/serial conversionson the data on a M-bit basis. Therefore, the received N-bit format datais format-converted to M-bit format data. The resulting data istransmitted to a buffer memory, and further subjected to theparallel/serial conversions and the like.

In accordance with a fourth aspect of the present invention, a datatransmission method of the present invention, which processes datathrough an N-bit bus, is provided with the steps of: reading M-bitformat data from a buffer memory; and converting the M-bit format datathus read to N-bit format data.

A data transmission apparatus corresponding to this data transmissionmethod, which processes data through an N-bit bus, is provided withmeans which reads M-bit format data from a buffer memory, and meanswhich converts the M-bit format data thus read to N-bit format data.

Here, the states of N-bit and M-bit are set in the same manner asdescribed above. These are typically exemplified by N=32 and M=24.

The data externally inputted to the data processing device andserial/parallel-converted is M-bit format data. The M-bit format data iswritten in a buffer memory. Further, the M-bit format data, read fromthe buffer memory, is format-converted to N-bit format data, and thentransmitted to the N-bit bus.

In accordance with a fifth aspect of the present invention, uponconverting the M-bit format data to the N-bit format data, the datatransmission method of the present invention inputs first dataconstituted by first, second and third packets, second data constitutedby fourth, fifth and sixth packets, third data constituted by seventh,eighth and ninth packets and fourth data constituted by tenth, eleventhand twelfth packets. Further, the data transmission method is providedwith a first control process of outputting fifth data constituted by thefirst, fourth, second and fifth packets, a second control process ofoutputting sixth data constituted by the third and sixth packets; athird control process of outputting seventh data constituted by theseventh, tenth, eighth and eleventh packets; a fourth control process ofoutputting eighth data constituted by the ninth and twelfth packets; anda fifth control process of inputting the sixth data and the eighth dataand outputting ninth data constituted by third, sixth, ninth and twelfthpackets.

A data transmission apparatus corresponding to this data transmissionmethod includes a conversion system from the M-bit format data to theN-bit format data which inputs first data constituted by first, secondand third packets, second data constituted by fourth, fifth and sixthpackets, third data constituted by seventh, eighth and ninth packets andfourth data constituted by tenth, eleventh and twelfth packets. Further,the conversion system is provided with a first control means whichoutputs fifth data constituted by the first, fourth, second and fifthpackets, a second control means which outputs sixth data constituted bythe third and sixth packets, a third control means which outputs seventhdata constituted by the seventh, tenth, eighth and eleventh packets, afourth control means which outputs eighth data constituted by the ninthand twelfth packets, and a fifth control means which receives the sixthdata and the eighth data, and outputs ninth data constituted by third,sixth, ninth and twelfth packets.

In this case, the relationship between the M-bit and N-bit isrepresented by M:N=3:4. That is, the relationship is represented by, forexample, 24 bits and 32 bits. When, upon sending data, the CPU executesa program for converting M-bit format data to N-bit format data, only 5instructions need to be executed, thereby making it possible to reducethe load to be imposed on the CPU.

In accordance with a sixth aspect of the present invention, uponconverting the N-bit format data to the M-bit format data, the datatransmission method of the present invention inputs first dataconstituted by first, second, third and fourth packets, second dataconstituted by fifth, sixth, seventh and eighth packets, and third dataconstituted by ninth, tenth, eleventh and twelfth packets. Further, thedata transmission method is provided with a first control process ofoutputting fourth data constituted by the first, fifth and secondpackets; a second control process of outputting fifth data constitutedby the third, seventh and fourth packets; a third control process ofinputting the second data and outputting sixth data constituted by thesixth, seventh and eighth packets after carrying out a shifting processto the right by one packet; a fourth control process of outputtingseventh data constituted by the ninth, sixth and tenth packets; and afifth control process of outputting eighth data constituted by theeleventh, eighth and twelfth packets.

A data transmission apparatus corresponding to this data transmissionmethod includes a conversion system from the N-bit format data to theM-bit format data which inputs first data constituted by first, second,third and fourth packets, second data constituted by fifth, sixth,seventh and eighth packets, and third data constituted by ninth, tenth,eleventh and twelfth packets. Further, the conversion system is providedwith a first control means which outputs fourth data constituted by thefirst, fifth and second packets, a second control means which outputsfifth data constituted by the third, seventh and fourth packets, a thirdcontrol means which receives the second data, and outputs sixth dataconstituted by the sixth, seventh and eighth packets after carrying outa shifting process to the right by one packet, a fourth control meanswhich outputs seventh data constituted by the ninth, sixth and tenthpackets, and a fifth control means which outputs eighth data constitutedby the eleventh, eighth and twelfth packets.

In this case, the relationship between the M-bit and N-bit isrepresented by M:N=3:4. That is, the relationship is represented by, forexample, 24 bits and 32 bits. When, upon receiving data, the CPUexecutes a program for converting N-bit format data to M-bit formatdata, only five instructions need to be executed, thereby making itpossible to reduce the load to be imposed on the CPU.

In accordance with a seventh aspect of the present invention, uponconverting the N-bit format data to the M-bit format data, the datatransmission method of the present invention is provided with a firstdata holding step of successively inputting first data constituted byfirst, second, third and fourth packets, second data constituted byfifth, sixth, seventh and eighth packets and third data constituted byninth, tenth, eleventh and twelfth packets, and holding the first,second and third data. The data transmission method is also providedwith a second data holding step of holding the fourth, eighth andtwelfth packets. The method is further provided with a data selectionstep of: inputting the data held in the first data holding step;allowing the higher-order one packet to shift to the second data holdingstep; allowing the lower-order three packets of the first, second andthird data to shift to a transmit control step as the fourth, fifth andsixth data; and when, upon completion of the processes, datacorresponding to three packets has been stored in the second dataholding step, switching processes to shift to the transmit control stepwith the data being used as the seventh data constituted by the fourth,eighth and twelfth packets. Moreover, the method is also provided with atransmit control step of successively transmitting the fourth, fifth,sixth and seventh data that have been shifted from the data selectionprocess to a buffer memory area.

A data transmission apparatus corresponding to this data transmissionmethod includes a conversion system from the N-bit format data to theM-bit format data which is provided with a first data holding meanswhich successively receives first data constituted by first, second,third and fourth packets, second data constituted by fifth, sixth,seventh and eighth packets and third data constituted by ninth, tenth,eleventh and twelfth packets, and holds the first, second and thirddata. The system is also provided with a second data holding means whichholds the fourth, eighth and twelfth packets. The system is furtherprovided with a data selection means which receives the data held in thefirst data holding means, allows the higher-order one packet to shift tothe second data holding means, allows the lower-order three packets ofthe first, second and third data to shift to a transmit control means asfourth, fifth and sixth data, and when, upon completion of theprocesses, data corresponding to three packets has been stored in thesecond data holding means, switches processes to shift to the transmitcontrol means with the data being used as the seventh data constitutedby the fourth, eighth and twelfth packets. Moreover, the system is alsoprovided with a transmit control means which successively transmits thefourth, fifth, sixth and seventh data that have been outputted from thedata selection means to a buffer memory area.

In this case, the relationship between the M-bit and N-bit isrepresented by M:N=3:4. That is, the relationship is represented by, forexample, 24 bits and 32 bits. In an attempt to achieve an apparatuswhich, upon sending data, can convert N-bit format data to M-bit formatdata, the apparatus can be achieved by a small number of elementsincluding only two registers, a transmit control means and a dataselection means; thus, it becomes possible to prevent an increase in theLSI circuit scale.

In accordance with an eighth aspect of the present invention, uponconverting the M-bit format data to the N-bit format data, the datatransmission method of the present invention inputs first dataconstituted by first, second and third packets, second data constitutedby fourth, fifth and sixth packets, third data constituted by seventh,eighth and ninth packets, and fourth data constituted by tenth, eleventhand twelfth packets. The data transmission method includes a transmitcontrol step of allowing the sequence to successively proceed to a dataselection step together with the first, second, third and fourth data.The method also includes a data selection step of: in the case when,among the data inputted at the transmit control step, the first data isinputted, allowing the sequence to proceed to the second data holdingstep, and in the case when the second, third and fourth data areinputted, respectively adding the first, second and third packets heldat the second data holding step to the higher-order packets to form thefifth, sixth and seventh data, and allowing the sequence to proceed tothe first data holding step. The method also includes a first dataholding step of holding the fifth, sixth and seventh data outputted fromthe data selection step. The method further includes a second dataholding step of holding the first data outputted at the data selectionstep.

A data transmission apparatus corresponding to this data transmissionmethod includes a conversion system from the M-bit format data to theN-bit format data which inputs first data constituted by first, secondand third packets, second data constituted by fourth, fifth and sixthpackets, third data constituted by seventh, eighth and ninth packets,and fourth data constituted by tenth, eleventh and twelfth packets. Theconversion system includes a transmit control means which successivelytransmits the first, second, third and fourth data to a data selectionmeans. The conversion system also has an arrangement in which data isinputted from the transmit control means. The conversion system furtherincludes the data selection means which, in the case when the first datais inputted, outputs the resulting data to the second data holdingmeans, and in the case when the second, third and fourth data areinputted, respectively adds the first, second and third packets held inthe second data holding means to the higher-order packets to form thefifth, sixth and seventh data so as to be outputted to the first dataholding means. The conversion system also includes a first data holdingmeans which receives and holds the fifth, sixth and seventh dataoutputted from the data selection means. The system further includes asecond data holding means which receives and holds the first dataoutputted from the data selection means.

In this case, the relationship between the M-bit and N-bit isrepresented by M:N=3:4. That is, the relationship is represented by, forexample, 24 bits and 32 bits. In an attempt to achieve an apparatuswhich, upon sending data, can convert N-bit format data to M-bit formatdata, the apparatus can be achieved by a small number of elementsincluding only two registers, a transmit control means and a dataselection means; thus, it becomes possible to prevent an increase in theLSI circuit scale.

In accordance with a ninth aspect of the present invention, a datatransmission, which processes data through an N-bit bus, divides M-bitformat data into packets of s-bits that correspond to the greatestcommon measure of M and N. The data transmission method is furtherprovided with a multi-format conversion step of converting q-number ofdata having an M-bit format constituted by s bits×p packets to p-numberof data having an N-bit format constituted by s bits×q packets, by usingrenumber of packets corresponding to the least common multiple of M÷s=pand N÷s=q as one unit.

In a data transmission apparatus corresponding to this data transmissionmethod that processes data through an N-bit bus, M-bit format data isdivided into packets of s-bits that correspond to the greatest commonmeasure of M and N. The data transmission apparatus is further providedwith a multi-format conversion means which converts q-number of datahaving an M-bit format constituted by s bits×p packets to p-number ofdata having an N-bit format constituted by s bits×q packets, by usingr-number of packets corresponding to the least common multiple of M÷s=pand N÷s=q as one unit.

In accordance with a tenth aspect of the present invention, a datatransmission method, which processes data through an N-bit bus, dividesN-bit format data into packets of s-bits that correspond to the greatestcommon measure of M and N. The data transmission method is furtherprovided with a multi-format conversion step of converting p-number ofdata having an N-bit format constituted by s bits×q packets to q-numberof data having an M-bit format constituted by s bits×p packets, by usingr-number of packets corresponding to the least common multiple of M÷s=pand N÷s=q as one unit.

In a data transmission apparatus corresponding to this data transmissionmethod that processes data through an N-bit bus, N-bit format data isdivided into packets of s-bits that correspond to the greatest commonmeasure of N and M. The data transmission apparatus is further providedwith a multi-format conversion means which converts p-number of datahaving an N-bit format constituted by s bits×q packets to q-number ofdata having an M-bit format constituted by s bits×p packets, by usingr-number of packets corresponding to the least common multiple of M÷s=pand N÷s=q as one unit.

With this arrangement, data having a format with an arbitrary bit widthcan be converted to N-bit format data so that a multi-format convertingprocess can be achieved.

With respect to the data to be used, the typical example is audio data.However, not limited to the audio data, the present invention is alsoapplicable to other multi-media processings, such as audio, image anddata processings, in portable terminals, digital cameras and the like.Thus, even in the case when one bus is shared by a number of interfaces,the efficiency of use of the bus at the time of transmitting data can beimproved. Moreover, it is also possible to cut the data memory arearequired for the CPU to carry out multi-media processes.

The foregoing and other aspects will become apparent from the followingdescription of the invention when considered in conjunction with theaccompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a block diagram that shows the entire structure of a datatransmission apparatus in accordance with embodiment 1 of the presentinvention;

FIG. 2 is a conceptual drawing that shows operations of a transmittingconversion program in accordance with embodiment 2 of the presentinvention;

FIG. 3 is a conceptual drawing that shows operations of a receivingconversion program in accordance with embodiment 3 of the presentinvention;

FIG. 4 is a conceptual drawing that shows a transmitting conversiondevice in accordance with embodiment 4 of the present invention;

FIG. 5 is a conceptual drawing that shows a receiving conversion devicein accordance with embodiment 5 of the present invention;

FIG. 6 is a conceptual drawing that shows a multi-format conversionmethod in accordance with embodiment 6 of the present invention;

FIG. 7 is a flow chart that shows an example of transmitting operationsof a data transmission apparatus in accordance with embodiment 1 of thepresent invention;

FIG. 8 is a flow chart that shows an example of receiving operations ofthe data transmission apparatus in accordance with embodiment 1 of thepresent invention;

FIG. 9 is a flow chart that shows an example of operations of atransmitting conversion program of a data transmission apparatus inaccordance with embodiment 2 of the present invention;

FIG. 10 is a flow chart that shows an example of operations of areceiving conversion program of a data transmission apparatus inaccordance with embodiment 3 of the present invention;

FIG. 11 is a flow chart that shows an example of operations of atransmitting conversion device in accordance with embodiment 4 of thepresent invention; and

FIG. 12 is a flow chart that shows an example of operations of areceiving conversion device in accordance with embodiment 5 of thepresent invention.

In all these figures, like components are indicated by the samenumerals.

DETAILED DESCRIPTION

Referring to Figures, the following description discusses preferredembodiments of a data transmission apparatus and a data transmissionmethod in accordance with the present invention.

(Embodiment 1)

FIG. 1 is a block diagram that shows the entire structure of a datatransmission apparatus in accordance with embodiment 1 of the presentinvention.

This data transmit apparatus is provided with an audio-data processingdevice 100, a CPU 110, a main memory area 120 and a data bus (32 bit)130. The audio-data processing device 100 is constituted by a formatconversion device 101, a buffer memory area 102, a parallel/serialconversion device 103 and a serial/parallel conversion device 104. Themain memory area 120 is provided with an encode/decode program area 121,a format conversion program area 122, a 24-bit audio-data area 123 and a32-bit format data area 124. Reference numeral 14 represents an ADconverter, 150 represents a DA converter, 160 represents a microphone,170 represents a speaker, 180 represents a user, 181 represents atransmission request and 182 represents a receiving request.

The audio-data processing device 100 is connected to the data bus (32bit) 130.

The format conversion device 101 functions to convert 32-bit format datato 24-bit audio data, and then to output the resulting data to thebuffer memory area 102. Moreover, it also functions to receive 24-bitaudio data from the buffer memory area 102, and, after converting thedata to 32-bit format data, to output the resulting data to the data bus130. The buffer memory area 102 is a memory having a 24-bit width, andfunctions to store 24 bit audio data.

The parallel/serial conversion device 103 functions to convert 24-bitaudio data inputted from the buffer memory area 102 to serial data, andto output the resulting data to the DA converter 150. Theserial/parallel conversion device 104 functions to convert serial datainputted from the AD converter 140 to 24-bit audio data, and to outputthe resulting data to the buffer memory area 102.

The CPU 110, which is connected to the data bus (32 bit) 130, functionsto carry out operations by using an encode/decode program and a formatconversion program in the main memory area 120.

The main memory area 120, which is connected to the data bus (32 bit),is provided with an encode/decode program area 121, a format conversionprogram area 122, a 24-bit audio data area 123 and a 32-bit format dataarea 124.

The encode/decode program area 121 includes an encode program whichcompresses 24-bit audio data into a predetermined compression formatsuch as an MP3 format, and a decode program which expands audio datacompressed by using a predetermined compression format such as the MP3format to 24-bit audio data.

The format conversion program are a 122 functions to receive 24-bitaudio data from the 24-bit audio data area 123, and, after convertingthe data to 32-bit form at data, to output the resulting data to the32-bit format data area 124. Moreover, it also functions to receive32-bit format data from the 32-bit format data area 124, and, afterconverting the data to 24-bit audio data, to output the resulting datato the 24-bit audio data area 123.

The 24-bit audio data area 123 functions to record 24-bit audio data.The 32-bit format data area 124 functions to record 32-bit format data.

The data bus (32 bit) 130, which is a data bus having a 32-bit width,connects the audio data processing device 100 to the CPU 110 as well asto the main memory area 120.

The AD converter 140 converts voice inputted from the microphone 160 toserial data, and outputs the data to the serial/parallel conversiondevice 104. The DA converter 150 functions to convert serial datainputted from the parallel/serial conversion device 103 to voice, and tooutput the voice to the speaker 170. The microphone 160 receives voiceinputted by the user, and outputs the voice to the AD converter 140. Thespeaker 170 functions to output voice inputted from the DA converter 150to space. The user 180 inputs a transmission request 181 and a receivingrequest 182 to the audio data processing device 100, inputs voice to themicrophone 160, and listens to voice outputted from the speaker 170. Thetransmission request 181 is a request signal that is inputted from theuser 180 to the audio data processing device 100. Upon receipt of thissignal, an audio data transmission flow is started. The receivingrequest 182 is a request signal that is inputted from the user 180 tothe audio data processing device 100. Upon receipt of this signal, anaudio data receiving flow is started.

Referring to a flow chart shown in FIG. 7, the following descriptiondiscusses an example of transmission operations in a data transmissionapparatus in accordance with the present embodiment having theabove-mentioned arrangement.

In a transmission request receiving process of step 701, the user 180inputs a transmission request 181 to the audio data processing device100.

Next, in a CPU audio decode process at step 702, by using a decodeprogram stored in the encode/decode program area 121, the CPU 110expands 24-bit audio data which has been read from the 24-bit audio dataarea 123, and compressed in a predetermined format.

In a 24-bit audio data recording process at step 703, the 24-bit audiodata, decoded by the CPU audio decode process of step 702, is recordedin the 24-bit audio data area 123.

Next, in a 32-bit format conversion process at step 704, the 24-bitaudio data is inputted from the 24-bit audio data area 123, andconverted to 32-bit format data.

Next, in a 32-bit format data recording process at step 705, the 32-bitformat data, converted by the 32-bit format conversion process at step704, is recorded in a 32-bit format data area 124.

Next, in a 32-bit format data transmission process at step 706, the32-bit format data, recorded in the 32-bit format data area 124, istransmitted to the audio data processing device 100.

In a 24-bit audio data conversion process at step 707, the 32-bit formatdata thus inputted is converted to 24-bit audio data, and outputted tothe buffer memory area 102.

Next, in a buffer memory recording process at step 708, the 24-bit audiodata, inputted from the format conversion device 101, is recorded in thebuffer memory area 102.

Next, in a parallel/serial conversion process at step 709, the 24-bitaudio data, inputted from the buffer memory area 102, is converted toserial data, and outputted to the DA converter 150.

Next, in a music reproducing process at step 710, the serial data,outputted through the parallel/serial conversion process 709, isconverted to voice by the DA converter 150, and outputted to the speaker170 so that the music is reproduced. The finish of this processcompletes the sequence of operations.

Referring to a flow chart shown in FIG. 8, the following descriptiondiscusses an example of receiving operations in the data transmissionapparatus in accordance with the present embodiment.

In a receiving request receiving process at step 801, the user 180inputs a receiving request 182 to the audio data processing device 100.

Next, in a music inputting process at step 802, the AD converter 140converts voice inputted by the user 180 through the microphone 160 toserial data, and outputs the resulting data to the serial/parallelconversion device 104.

In a serial/parallel conversion process at step 803, the serial data,inputted from the AD converter 140, is converted to 24-bit audio data,and outputted to the buffer memory area 102.

Next, in a buffer memory recording process at step 804, the 24-bit audiodata, inputted from the serial/parallel conversion device 104, isrecorded in the buffer memory area 102.

In a 32-bit format conversion process at step 805, the 24-bit audiodata, inputted from the buffer memory area 102, is converted to 32-bitformat data.

Next, in a 32-bit format data transmission process at step 806, the32-bit format data, converted by the 32-bit format conversion process atstep 805, is transferred to the 32-bit format data area 124.

Next, in a 24-bit audio data conversion process at step 807, 32-bitformat data is inputted from the 32-bit format data area 124, andconverted to 24-bit audio data.

In a 24-bit audio data data-recording process at step 808, the 24-bitaudio data, converted by the 24-bit audio data conversion process atstep 807, is recorded in the 24-bit audio data area 123.

Next, in a CPU audio encode process at step 809, by using an encodeprogram recorded in the encode/decode program area 121, the CPU 110compresses the 24-bit audio data recorded in the 24-bit audio data area123 to a predetermined format. The finish of this process completes thesequence of operations.

With the above-mentioned arrangement, in the audio datasending/receiving operations, when the 24-bit audio data isbus-transmitted, the transmitting process is carried out after the24-bit audio data has been converted to 32-bit format data. This makesit possible to provide special effects for improving the efficiency ofuse of the bus.

(Embodiment 2)

FIG. 2 is a conceptual drawing that shows operations of a transmittingconversion program in accordance with embodiment 2 of the presentinvention.

Data A 200 is 24-bit audio data constituted by packets of A1, A2 and A3,each having 8 bits. Data B 201 is 24-bit audio data constituted bypackets of B1, B2 and B3, each having 8 bits. Data C 202 is 24-bit audiodata constituted by packets of C1, C2 and C3, each having 8 bits. Data D203 is 24-bit audio data constituted by packets of D1, D2 and D3, eachhaving 8 bits. These data are inputted to a transmitting conversionprogram.

Data α204 is 32-bit format data constituted by packets of A1, B1, A2 andB2, each having 8 bits. This is outputted as the resulting data afteroperations using data A200 and data B201 as input data. Data AB 205 isconstituted by packets of A3 and B3, each having 8 bits. This data is32-bit format data with the higher-order 16 bits being defined as “Don'tcare”, and outputted after operations carried out by using data A200 andB201 as input data. Data ββ206 is 32-bit format data constituted bypackets of C1, D1, C2 and D2, each having 8 bits. This data β206 isoutputted as the resulting data after operations using data C202 anddata D203 as input data. Data CD 207 is constituted by packets of C3 andD3, each having 8 bits. This data is 32-bit format data with thehigher-order 16 bits being defined as “Don't care”, and outputted afteroperations carried out by using data C202 and D203 as input data. Dataγ208 is 32-bit format data constituted by packets of A3, B3, C3 and D3,each having 8 bits. This data γ208 is outputted as the resulting dataafter operations using data AB205 and data CD207 as input data.

Referring to a flow chart shown in FIG. 9, the following descriptiondiscusses an example of operations in the data transmission apparatus inaccordance with the present embodiment.

In a data input process at step 901, data A200, data B201, data C202 anddata D203 are inputted from the 24-bit audio data area 123.

Next, in a data A/B calculation process (1) at step 902, with respect tolower-order 16 bits of data A200 and data B201, an interleaveinstruction is executed on a byte basis so that data α204 is outputted.Successively, in a data α recording process at step 903, the data α204,outputted in the data A/B calculation process (1) at step 902, isrecorded in the 32-bit format data area 124 ([1]).

Next, in a data A/B calculation process (2) at step 904, with respect tohigher-order 16 bits of data A200 and data B201, an interleaveinstruction is executed on a byte basis so that data AB205 is outputted.Successively, in a data AB storing process at step 905, the data AB205,outputted in the data A/B calculation process (2) at step 904, is storedin a data register ([2]).

Next, in a data C/D calculation process (1) at step 906, with respect tolower-order 16 bits of data C202 and data D203, an interleaveinstruction is executed on a byte basis so that data β206 is outputted.Successively, in a data β recording process at step 907, the data β206,outputted in the data C/D calculation process (1) at step 906, isrecorded in the 32-bit format data area 124 ([3]).

Next, in a data C/D calculation process (2) at step 908, with respect tohigher-order 16 bits of data C202 and data D203, an interleaveinstruction is executed on a byte basis so that data CD207 is outputted.Successively, in a data CD storing process at step 909, the data CD207,outputted in the data C/D calculation process (2) at step 908, is storedin a data register ([4]).

Next, in a data AB/CD calculation process at step 910, with respect tolower-order 16 bits of data AB205 and data CD207, an interleaveinstruction is executed on a half-word basis so that data γ208 isoutputted. Successively, in a data γrecording process at step 911, thedata γ208, outputted in the data AB/CD calculation process at step 910,is recorded in the 32-bit format data area 124 ([5]).

In a decode completion determining process at step 912, it is determinedwhether or not the CPU audio decode process at step 702 of FIG. 7 hasbeen completed. When this process has not been completed, the sequenceproceeds to the data input process at step 901, and when it has beencompleted, the operations are completed.

With the above-mentioned arrangement, in the transmission operation ofaudio data, when the CPU executes the program for converting 24-bitaudio data to 32-bit format data, only five instructions [1] to [5] arerequired. By properly designing the program in this manner, it becomespossible to provide specific effects for reducing the load imposed onthe CPU.

(Embodiment 3)

FIG. 3 is a conceptual drawing that shows operations of a receivingconversion program in accordance with embodiment 3 of the presentinvention.

Data α300 is 32-bit format data constituted by packets of A1, A3, B1 andB3, each having 8 bits. Data β301 is 32-bit format data constituted bypackets of A2, C2, B2 and D2, each having 8 bits. Data γ302 is 32-bitformat data constituted by packets of C1, C3, D1 and D3, each having 8bits. These data are inputted to a receiving conversion program.

Data β′ 303 is constituted by packets of C2, B2 and D2, each having 8bits. This data is 32-bit format data with the higher-order 8 bits beingdefined as “Don't care”, and outputted after operations carried out byusing data β301 as input data. Data A304 is constituted by packets ofA1, A2 and A3, each having 8 bits. This data is 32-bit format data withthe higher-order 8 bits being defined as “Don't care”, and outputtedafter operations carried out by using data α300 and data β301 as inputdata. Data B305 is constituted by packets of B1, B2 and B3, each having8 bits. This data is 32-bit format data with the higher-order 8 bitsbeing defined as “Don't care”, and outputted after operations carriedout by using data α300 and data β301 as input data. Data C306 isconstituted by packets of C1, C2 and C3, each having 8 bits. This datais 32-bit format data with the higher-order 8 bits being defined as“Don't care”, and outputted after operations carried out by using dataγ302 and data β′ 303 as input data. Data D307 is 32-bit format dataconstituted by packets of D1, D2 and D3, each having 8 bits. This dataD307 is outputted as the resulting data after operations using data γ302and data β′ 303 as input data.

Referring to a flow chart shown in FIG. 10, the following descriptiondiscusses an example of operations in the data transmission apparatus inaccordance with the present embodiment.

In a data input process at step 1001, data α300, data β301 and data γ302are inputted from the 32-bit format data area 124.

Next, in a data α/β calculation process (1) at step 1002, with respectto lower-order 16 bits of data α300 and data β301, an interleaveinstruction is executed on a byte basis so that data A304 is outputted.Successively, in a data A recording process at step 1003, the data A304,outputted in the data α/β calculation process (1) at step 1002, isrecorded in the 24-bit audio data area 123 ([1]).

Next, in a data α/β calculation process (2) at step 1004, with respectto higher-order 16 bits of data α300 and data β301, an interleaveinstruction is executed on a byte basis so that data B305 is outputted.Successively, in a data B recording process at step 1005, the data B305,outputted in the data α/β calculation process (2) at step 1004, isrecorded in the 24-bit audio data area 123 ([2]).

Next, in a data β calculation process at step 1006, an instruction forshifting data β301 to the right by 8 bits is executed to output data β′303 ([3]).

Next, in a data γ/β′ calculation process (1) at step 1007, with respectto higher-order 16 bits of data γ302 and data β′ 303, an interleaveinstruction is executed on a byte basis so that data C306 is outputted.Successively, in a data C recording process at step 1008, the data C306,outputted at the data γ/β′ calculation process (1) at step 1007, isrecorded in the 24-bit audio data area 123 ([4]).

Next, in a data γ/β′ calculation process (2) at step 1009, with respectto lower-order 16 bits of data γ302 and data β′ 303, an interleaveinstruction is executed on a byte basis so that data D307 is outputted.Successively, in a data D recording process at step 1010, the data D307,outputted at the data γ/β′ calculation process (2) at step 1009, isrecorded in the 24-bit audio data area 123 ([5]).

In a voice-input completion determining process at step 1011, it isdetermined whether or not the music inputting process at step 802 ofFIG. 8 has been completed. When this process has not been completed, thesequence proceeds to the data input process at step 1001, and when ithas been finished, the operations are completed.

With the above-mentioned arrangement, in the receiving operation ofaudio data, when the CPU executes the program for converting 32-bitformat data to 24-bit audio data, only five instructions [1] to [5] arerequired. By properly designing the program in this manner, it becomespossible to provide specific effects for reducing the load imposed onthe CPU.

(Embodiment 4)

FIG. 4 is a conceptual drawing that shows a transmitting conversiondevice in accordance with embodiment 4 of the present invention. In thisFigure, the same blocks as those in FIG. 1 explained in embodiment 1 areindicated by the same reference numerals, and the description thereof isomitted.

A format conversion device 101 is constituted by a data holding means(1) 400, a data holding means (2) 401, a transmit control means 402 anda data selection means 403.

The data holding means (1) 400 is a register having a 32-bit width, andfunctions to hold data that is inputted to the format conversion device101. The data holding means (2) 401 is a register having a 24-bit width,and functions to hold the higher-order 8 bits of the data holding means(1) 400 selected by the data selection means 403 in succession from thelower-order bits.

The transmit control means 402 functions to transmit 24-bit audio dataselected by the data selection means 403 to a buffer memory area 102 insuccession. The data selection means 403 functions to transmit thelower-order 24 bits of the data holding means (1) 400 to the transmitcontrol means 402, and also to transmit the higher-order 8 bits thereofto the data holding means (2) 401. Moreover, it also has such a functionthat, when data corresponding to three packets has stored in the dataholding means (2) 401, 24-bit data of the data holding means (2) 401 istransmitted to the transmit control means 402.

Data α410 is 32-bit format data constituted by packets of A1, A2, A3 andD1, each having 8 bits. Data β411 is 32-bit format data constituted bypackets of B1, B2, B3 and D2, each having 8 bits. Data γ412 is 32-bitformat data constituted by packets of C1, C2, C3 and D3, each having 8bits. These data are inputted to the transmit conversion apparatus.

Data A420 is 24-bit audio data constituted by packets of A1, A2 and A3,each having 8 bits. Data B421 is 24-bit audio data constituted bypackets of B1, B2 and B3, each having 8 bits. Data C422 is 24-bit audiodata constituted by packets of C1, C2 and C3, each having 8 bits. DataD423 is 24-bit audio data constituted by packets of D1, D2 and D3, eachhaving 8 bits. These data are transmitted to a buffer memory area 102 bythe transmit control means 402.

Referring to a flow chart shown in FIG. 11, the following descriptiondiscusses an example of operations in the data transmit apparatus inaccordance with the present embodiment.

In a data a input process at step 1101, data α410 is written in the dataholding means (1) 400.

Next, in a data a selection process at step 1102, the lower-order 24bits of the data holding means (1) 400 are transmitted to the transmitcontrol means 402, while the higher-order 8 bits thereof are transmittedto the lower-order 8 bits of the data holding means (2) 401, by the dataselection means 403.

Next, in a data A transmit process at step 1103, 24-bit audio dataselected by the α selection process at step 1102 is transmitted to thebuffer memory area 102.

In a data β input process at step 1104, data β 411 is written in thedata holding means (1) 400.

Next, in a data β selection process at step 1105, the lower-order 24bits of the data holding means (1) 400 are transmitted to the transmitcontrol means 402, while the higher-order 8 bits thereof are transmittedto the middle-order 8 bits of the data holding means (2) 401, by thedata selection means 403.

Next, in a data B transmit process at step 1106, 24-bit audio dataselected by the β selection process at step 1105 is transmitted to thebuffer memory area 102.

In a data γ input process at step 1107, data γ412 is written in the dataholding means (1) 400.

Next, in a data γ selection process at step 1108, the lower-order 24bits of the data holding means (1) 400 are transmitted to the transmitcontrol means 402, while the higher-order 8 bits thereof are transmittedto the higher-order 8 bits of the data holding means (2) 401, by thedata selection means 403.

Next, in a data C transmit process at step 1109, 24-bit audio dataselected by the data γ selection process at step 1108 is transmitted tothe buffer memory area 102.

Next, in a data D selection process at step 1110, 24-bit audio data ofthe data holding means (2) 401 is transmitted to the transmit controlmeans 402 by the data selection means 403.

Next, in a data D transmit process at step 1111, 24-bit audio dataselected by the data D selection process at step 1110 is transmitted tothe buffer memory area 102.

In a transmission data completion determining process at step 1112, itis determined whether or not the 32-bit format data transmit process atstep 706 of FIG. 7 has been completed. When this process has not beencompleted, the sequence proceeds to the data a input process at step1101, and when it has been completed, the operations are completed.

With the above-mentioned arrangement, in an attempt to achieve a devicewhich converts 32-bit format data to 24-bit audio data in thetransmitting operation of audio data, the device can be achieved byusing a small number of circuits including only the two registers, thetransmit control means and the data selection means. By properlydesigning the device structure in this manner, it becomes possible toprovide specific effects for preventing an increase in the LSI circuitscale.

(Embodiment 5)

FIG. 5 is a conceptual drawing that shows a receiving conversion devicein accordance with embodiment 5 of the present invention. In thisFigure, the same blocks as those in FIG. 1 explained in embodiment 1 areindicated by the same reference numerals, and the description thereof isomitted.

A format conversion device 101 is constituted by a data holding means(1) 500, a data holding means (2) 501, a transmit control means 502 anda data selection means 503.

The data holding means (1) 500 is a register having a 32-bit width, andfunctions to hold data that is inputted to the data selection means 503.The data holding means (2) 501 is a register having a 24-bit width, andfunctions to hold data A520 that is selected by the data selection means503.

The transmit control means 502 functions to successively receive 24-bitaudio data from a buffer memory area 102, and to output the resultingdata to the data selection means 503. In the case when the 24-bit audiodata, inputted from the transmit control means 502, is data A520, thedata selection means 503 transmits the data to the data holding means(2) 501, and in the case of data B521, data C522 and data D523, it addseach packet of A1, A2 and A3 that have been held in the dada holdingmeans (2) to the higher-order bit of each of the data, and transmits theresulting data to the data holding means (1) 500.

Data α510 is 32-bit format data constituted by packets of B1, B2, B3 andA1, each having 8 bits. Data β511 is 32-bit format data constituted bypackets of C1, C2, C3 and A2, each having 8 bits. Data γ512 is 32-bitformat data constituted by packets of D1, D2, D3 and A3, each having 8bits. These data are transmitted to a 32-bit format data area 124 fromthe format conversion device 101.

Data A520 is 24-bit audio data constituted by packets of A1, A2 and A3,each having 8 bits. Data B521 is 24-bit audio data constituted bypackets of B1, B2 and B3, each having 8 bits. Data C522 is 24-bit audiodata constituted by packets of C1, C2 and C3, each having 8 bits. DataD523 is 24-bit audio data constituted by packets of D1, D2 and D3, eachhaving 8 bits. These data are inputted from the buffer memory area 102by the transmit control means 502.

Referring to a flow chart shown in FIG. 12, the following descriptiondiscusses an example of operations in the data transmission apparatus inaccordance with the present embodiment.

In a data A input process at step 1201, data A520 is inputted to thetransmit control means 502 from the buffer memory area 102, and theresulting data is outputted to the data selection means 503.

Next, in a data A selection process at step 1202, the data A520 istransmitted to the data holding means (2) 501 from the data selectionmeans 503.

In a data B input process at step 1203, data B521 is inputted to thetransmit control means 502 from the buffer memory area 102, and theresulting data is outputted to the data selection means 503.

Next, in a data B selection process at step 1204, the data selectionmeans 503 transmits data B521 to the lower-order 24 bits of the dataholding means (1) 500, and also transmits the lower-order 8 bits of thedata holding means (2) 501 to the higher-order 8 bits of the dataholding means (1) 500.

Next, in a data α selection process at step 1205, data α510 istransmitted to the 32-bit format data area 124 from the data holdingmeans (1) 500.

Next, in a data C input process at step 1206, data C522 is inputted tothe transmit control means 502 from the buffer memory area 102, and theresulting data is outputted to the data selection means 503.

Next, in a data C selection process at step 1207, the data selectionmeans 503 transmits data C522 to the lower-order 24 bits of the dataholding means (1) 500, and also transmits the middle-order 8 bits of thedata holding means (2) 501 to the higher-order 8 bits of the dataholding means (1) 500.

Next, in a data β transmit process at step 1208, data β 511 istransmitted to the 32-bit format data area 124 from the data holdingmeans (1) 500.

Next, in a data D input process at step 1209, data D523 is inputted tothe transmit control means 502 from the buffer memory area 102, and theresulting data is outputted to the data selection means 503.

Next, in a data D selection process at step 1210, the data selectionmeans 503 transmits data D523 to the lower-order 24 bits of the dataholding means (1) 500, and also transmits the higher-order 8 bits of thedata holding means (2) 501 to the higher-order 8 bits of the dataholding means (1) 500.

Next, in a data γ transmit process at step 1211, data γ512 istransmitted to the 32-bit format data area 124 from the data holdingmeans (1) 500.

In a receiving data completion determining process at step 1212, it isdetermined whether or not the buffer-memory recording process 804 hasbeen completed. When this process has not been completed, the sequenceproceeds to the data A input process at step 1201, and when it has beencompleted, the operations are completed.

With the above-mentioned arrangement, in an attempt to achieve a devicewhich converts 32-bit format data to 24-bit audio data in the receivingoperation of audio data, the device can be achieved by using a smallnumber of circuits including only the two registers, the transmitcontrol means and the data selection means. By properly designing thedevice structure in this manner, it becomes possible to provide specificeffects for preventing an increase in the LSI circuit scale.

(Embodiment 6)

FIG. 6 is a conceptual drawing that shows a multi-format conversionmethod in accordance with embodiment 6 of the present invention.

A 24-bit audio format 600 is provided with a unit corresponding to 4data each of which is obtained by dividing 24-bit audio data into 8bits×3 packets, and a 32-bit format (1) 601 is provided with a unitcorresponding to 3 data each of which is 32-bit format data constitutedby 8 bits×4 packets. A 24-bit format conversion method 602, whichrelates to a method for transmitting data through a 32-bit bus, divides24-bit audio data into packets of 8 bits that correspond to the greatestcommon measure of 24 and 32. Here, this format conversion method carriesout a mutual conversion process between 24 bits (3 packets)×4 data and32 bits (4 packets)×3 data, by using 12 packets that correspond to theleast common multiple of 24÷8=3 and 32÷8=4 as one unit.

A 20-bit audio format 610 is a unit corresponding to 8 data each ofwhich is obtained by dividing 20-bit audio data into 4 bits×5 packets,and a 32-bit format (2) 611 is a unit corresponding to 5 data of 32-bitformat data constituted by 4 bits×8 packets. A 20-bit format conversionmethod 612, which relates to a method for transmitting data through a32-bit bus, divides 20-bit audio data into packets of 4 bits thatcorrespond to the greatest common measure of 20 and 32. Here, thisformat conversion method carries out a mutual conversion process between20 bits (5 packets)×8 data and 32 bits (8 packets)×5 data, by using 40packets that correspond to the least common multiple of 20÷4=5 and32÷4=8 as one unit.

A 18-bit audio format 620 is a unit corresponding to 16 data each ofwhich is obtained by dividing 18-bit audio data into 2 bits×9 packets,and a 32-bit format (3) 621 is a unit corresponding to 9 data of 32-bitformat data constituted by 2 bits×16 packets. A 18-bit format conversionmethod 622, which relates to a method for transmitting data through a32-bit bus, divides 18-bit audio data into packets of 2 bits thatcorrespond to the greatest common measure of 18 and 32. Here, thisformat conversion method carries out a mutual conversion process between18 bits (9 packets)×16 data and 32 bits (16 packets)×9 data, by using144 packets that correspond to the least common multiple of 18÷2=9 and32÷2=16 as one unit.

With the above-mentioned arrangements, it is possible to achieveconversion methods of audio formats having 24, 20 and 18 bit widths to32-bit format data. Moreover, with respect to audio data having anotherbit width, it is possible to achieve a conversion method based upon thesame principle. In this manner, it is possible to obtain special effectsfor providing a format conversion method that is applicable to amulti-bit audio format.

Moreover, in the case of transmitting data through a 64-bit bus, thesame principle as the above-mentioned conversion method can be used. Byusing twice the number of packets as one unit, it is possible to providea format conversion method that is applicable to a multi-bit audioformat data in the same manner.

As described above, in the embodiments of the present invention, whendata is transmitted through a 32-bit bus, for example, during sendingand receiving operations of audio data, the efficiency of use of the buscan be improved by converting 24-bit audio data to 32-bit format dataupon transmission through the bus. Moreover,upon executing a program forthe conversion, only the five instructions need to be executed. Byproperly designing the program in this manner, it is possible to reducethe load to be imposed on the CPU. Moreover, in an attempt to achieve aconversion device for carrying out the conversion, by designing thestructure of the device so as to be formed by using a small number ofcircuits including only the two registers, transmit control means anddata selection means, it becomes possible to prevent an increase in thescale of the LSI circuit. Furthermore, since an appropriate conversionmethod can be achieved for audio data having another bit width such as24, 20 and 18 bit widths, it is possible to provide a conversion methodthat is applicable to a multi-bit audio format. Even in the case whendata is transmitted through a 64-bit bus, it is possible to provide aconversion method that is applicable to a multi-bit audio format, byusing the same principle as the 32-bit bus.

In summary, the following effects can be obtained: In the future, themulti-media industries are expected to be further developed in widerfields, and data-bus sharing that involves various pieces of applicationsoftware is expected. Under these circumstances, by improving theefficiency of use of 32- and 64-bit peripheral data buses, moreprocesses can be carried out simultaneously in parallel with each other.Moreover, it is also possible to cut the data memory area required forthe CPU to carry out multi-media processes.

As described above, in accordance with the present invention, upontransmitting data through an N-bit bus, M-bit format data ispreliminarily format-converted to N-bit format data prior to thetransmission. Then, the N-bit format data that has been format-convertedis transmitted through the N-bit bus. Thus, the N-bit bus can beeffectively utilized to its full extent, and the efficiency of use ofthe bus can be improved.

Moreover, the program to be used for the conversion is designed in sucha manner that only the five instructions are required upon executing theprogram; therefore, it becomes possible to reduce the load to be imposedon the CPU. Furthermore, in an attempt to achieve a conversion devicefor carrying out the conversion, the device can be achieved by using asmall number of circuits including only two registers, a transmitcontrol means and a data selection means; therefore, it is possible toprevent an increase in the LSI circuit scale.

Furthermore, data having a format with an arbitrary bit width can beconverted to N-bit format data so that a multi-format converting processcan be achieved. Here, in multi-media fields, data-bus sharing thatinvolves various pieces of application software is expected. Under thesecircumstances, more processes can be simultaneously executed in parallelwith each other. With respect to the data memory area required for theCPU to execute multi-media processes, it becomes possible to cut thearea.

From the above description it will be apparent that the presentinvention provides.

1. A data transmission method, which processes data through an N-bitbus, comprising the steps of: converting M-bit format data, which is abasic data unit for data processing, to N-bit format data, which is abasic data unit for data transmission; and transmitting the convertedN-bit format data to a data processing device. wherein with respect to aconversion system from the M-bit format data to the N-bit format data,first data constituted by first, second and third packets, second dataconstituted by fourth, fifth and sixth packets, third data constitutedby seventh, eighth and ninth packets and fourth data constituted bytenth, eleventh and twelfth packets are inputted, the method comprising:a first control process of outputting fifth data constituted by thefirst, fourth, second and fifth packets; a second control process ofoutputting sixth data constituted by the third and sixth packets; athird control process of outputting seventh data constituted by theseventh, tenth, eighth and eleventh packets; a fourth control process ofoutputting eighth data constituted by the ninth and twelfth packets; anda fifth control process of inputting the sixth data and, the eighth dataand outputting ninth data constituted by third, sixth, ninth and twelfthpackets.
 2. A data transmission method, which processes data through anN-bit bus, comprising the steps of: reading M-bit format data, which isa basic data unit for data processing, from a buffer memory; andconverting the M-bit format data thus read to N-bit format data, whichis a basic data unit for data transmission, wherein with respect to aconversion system from the M-bit format data to the N-bit format data,first data constituted by first, second and third packets, second dataconstituted by fourth, fifth and sixth packets, third data constitutedby seventh, eighth and ninth packets and fourth data constituted bytenth, eleventh and twelfth packets are inputted, the method comprising:a first control process of outputting fifth data constituted by thefirst, fourth, second and fifth packets; a second control process ofoutputting sixth data constituted by the third and sixth packets; athird control process of outputting seventh data constituted by theseventh, tenth, eighth and eleventh packets; a fourth control process ofoutputting eighth data constituted by the ninth and twelfth packets; anda fifth control process of inputting the sixth data and the eighth dataand outputting ninth data constituted by third, sixth, ninth and twelfthpackets.
 3. A data transmission method, which processes data through anN-bit bus, comprising the steps of: transmitting N-bit format data,which is a basic data unit for data transmission, from a data processingdevice; and converting the transmitted N-bit format data to M-bit formatdata, which is a basic data unit for data processing, wherein withrespect to a conversion system from the N-bit format data to the M-bitformat data, first data constituted by first, second, third and fourthpackets, second data constituted by fifth, sixth, seventh and eighthpackets, and third data constituted by ninth, tenth, eleventh andtwelfth packets are inputted, the method comprising: a first controlprocess of outputting fourth data constituted by the first, fifth andsecond packets; a second control process of outputting fifth dataconstituted by the third, seventh and fourth packets; a third controlprocess of inputting the second data, and outputting sixth dataconstituted by the sixth, seventh and eighth packets after carrying outa shifting process to the right by one packet; a fourth control processof outputting seventh data constituted by the ninth, sixth and tenthpackets; and a fifth control process of outputting eighth dataconstituted by the eleventh, eighth and twelfth packets.
 4. A datatransmission method, which processes data through an N-bit bus,comprising the steps of: converting N-bit format data, which is a basicdata unit for data transmission, to M-bit format data, which is a basicdata unit for data processing; and writing the converted M-bit formatdata in a buffer memory, wherein with respect to a conversion systemfrom the N-bit format data to the M- bit format data, first dataconstituted by first, second, third and fourth packets, second dataconstituted by fifth, sixth, seventh and eighth packets, and third dataconstituted by ninth, tenth, eleventh and twelfth packets are inputted,the method comprising: a first control process of outputting fourth dataconstituted by the first, fifth and second packets; a second controlprocess of outputting fifth data constituted by the third, seventh andfourth packets; a third control process of inputting the second data,and outputting sixth data constituted by the sixth, seventh and eighthpackets after carrying out a shifting process to the right by onepacket; a fourth control process of outputting seventh data constitutedby the ninth, sixth and tenth packets; and a fifth control process ofoutputting eighth data constituted by the eleventh, eighth and twelfthpackets.
 5. A data transmission method, which processes data through anN-bit bus, comprising the steps of: converting N-bit format data, whichis a basic data unit for data transmission, to M-bit format data, whichis a basic data unit for data processing; and writing the convertedM-bit format data in a buffer memory, wherein with respect to aconversion system from the N-bit format data to the M-bit format data,first data constituted by first, second, third and fourth packets,second data constituted by fifth, sixth, seventh and eighth packets, andthird data constituted by ninth, tenth, eleventh and twelfth packets aresuccessively inputted, the method comprising: a first data holding stepof holding the first, second and third data; a second data holding stepof holding the fourth, eighth and twelfth packets; a data selection stepof inputting the data held in the first data holding step; allowing thehigher-order one packet to shift to the second data holding step;allowing the lower-order three packets of the first, second and thirddata to shift to a transmit control step as the fourth, fifth and sixthdata; and when, upon completion of the steps, data corresponding tothree packets has been stored in the second data holding step, switchingsteps to shift to the transmit control step with the data being used asthe seventh data constituted by the fourth, eighth and twelfth packets;and a transmit control step of successively transmitting the fourth,fifth, sixth and seventh data that have been shifted from the dataselection step to a buffer memory area.
 6. A data transmission method,which processes data through an N-bit bus, comprising the steps of:reading M-bit format data, which is a basic data unit for dataprocessing, from a buffer memory; and converting the M-bit format datathus read to N-bit format data, which is a basic data unit for datatransmission, wherein with respect to a conversion system from the M-bitformat data to the N-bit format data, first data constituted by first,second and third packets, second data constituted by fourth, fifth andsixth packets, third data constituted by seventh, eighth and ninthpackets, and fourth data constituted by tenth, eleventh and twelfthpackets are inputted, the method comprising: a transmit control step ofallowing the sequence to successively proceed to a data selection steptogether with the first, second, third and fourth data; a data selectionstep of, in the case when, among the data inputted at the transmitcontrol step, the first data is inputted, allowing the sequence toproceed to a second data holding step, and in the case when the second,third and fourth data are inputted, respectively adding the first,second and third packets held at the second data holding step to thehigher-order packets to form the fifth, sixth and seventh data, andallowing the sequence to proceed to a first data holding step; the firstdata holding step of holding the fifth, sixth and seventh data outputtedfrom the data selection step; and the second data holding step ofholding the first data outputted at the data selection step.
 7. A datatransmission apparatus, which processes data through an N-bit bus,comprising: means which converts M-bit format data, which is a basicdata unit for data processing, to N-bit format data, which is a basicdata unit for data transmission; and means which transmits the convertedN-bit format data to a data processing device, wherein with respect tothe conversion system from the M-bit format data to the N-bit formatdata, first data constituted by first, second and third packets, seconddata constituted by fourth, fifth and sixth packets, third dataconstituted by seventh, eighth and ninth packets and fourth dataconstituted by tenth, eleventh and twelfth packets are inputted, theapparatus comprising: first control means which outputs fifth dataconstituted by the first, fourth, second and fifth packets; secondcontrol means which outputs sixth data constituted by the third andsixth packets; third control means which outputs seventh dataconstituted by the seventh, tenth, eighth and eleventh packets; fourthcontrol means which outputs eighth data constituted by the ninth andtwelfth packets; and fifth control means which receives the sixth dataand the eighth data and outputs ninth data constituted by third, sixth,ninth and twelfth packets.
 8. A data transmission apparatus, whichprocesses data through an N-bit bus, comprising: means which reads M-bitformat data, which is a basic data unit for data processing, from abuffer memory; and means which converts the M-bit format data thus readto N-bit format data, which is a basic data unit for data transmission,wherein with respect to the conversion system from the M-bit format datato the N-bit format data, first data constituted by first, second andthird packets, second data constituted by fourth, fifth and sixthpackets, third data constituted by seventh, eighth and ninth packets andfourth data constituted by tenth, eleventh and twelfth packets areinputted, the apparatus comprising: first control means which outputsfifth data constituted by the first, fourth, second and fifth packets;second control means which outputs sixth data constituted by the thirdand sixth packets; third control means which outputs seventh dataconstituted by the seventh, tenth, eighth and eleventh packets; fourthcontrol means which outputs eighth data constituted by the ninth andtwelfth packets; and fifth control means which receives the sixth dataand the eighth data and outputs ninth data constituted by third, sixth,ninth and twelfth packets.
 9. A data transmission apparatus, whichprocesses data through an N-bit bus, comprising: means which transmitsN-bit format data, which is a basic data unit for data transmission,from a data processing device; and means which converts the transmittedN-bit format data to M-bit format data, which is a basic data unit fordata processing, wherein with respect to the conversion system from theN-bit format data to the M-bit format data, first data constituted byfirst, second; third and fourth packets, second data constituted byfifth, sixth, seventh and eighth packets, and third data constituted byninth, tenth, eleventh and twelfth packets are inputted, the apparatuscomprising: first control means which outputs fourth data constituted bythe first, fifth and second packets; second control means which outputsfifth data constituted by the third, seventh and fourth packets; thirdcontrol means which receives the second data, and outputs sixth dataconstituted by the sixth, seventh and eighth packets after carrying outa shifting process to the right by one packet; fourth control meanswhich outputs seventh data constituted by the ninth, sixth and tenthpackets; and fifth control means which outputs eighth data constitutedby the eleventh, eighth and twelfth packets.
 10. A data transmissionapparatus, which processes data through an N-bit bus, comprising: meanswhich converts N-bit format data, which is a basic data unit for datatransmission, to M-bit format data, which is a basic data unit for dataprocessing; and means which writes the converted M-bit format data in abuffer memory, wherein with respect to the conversion system from theN-bit format data to the M-bit format data, first data constituted byfirst, second, third and fourth packets, second data constituted byfifth, sixth, seventh and eighth packets, and third data constituted byninth, tenth, eleventh and twelfth packets are inputted, the apparatuscomprises: first control means which outputs fourth data constituted bythe first, fifth and second packets; second control means which outputsfifth data constituted by the third, seventh and fourth packets; thirdcontrol means which receives the second data, and outputs sixth dataconstituted by the sixth, seventh and eighth packets after carrying outa shifting process to the right by one packet; fourth control meanswhich outputs seventh data constituted by the ninth, sixth and tenthpackets; and fifth control means which outputs eighth data constitutedby the eleventh, eighth and twelfth packets.
 11. A data transmissionapparatus, which processes data through an N-bit bus, comprising: meanswhich converts N-bit format data, which is a basic data unit for datatransmission, to M-bit format data, which is a basic data unit for dataprocessing; and means which writes the converted M-bit format data in abuffer memory, wherein with respect to the conversion system from theN-bit format data to the M-bit format data, first data constituted byfirst, second, third and fourth packets, second data constituted byfifth, sixth, seventh and eighth packets, and third data constituted byninth, tenth, eleventh and twelfth packets are successively inputted,the apparatus comprising: first data holding means which holds thefirst, second and third data; second data holding means which holds thefourth, eighth and twelfth packets; data selection means which receivesthe data held in the first data holding step, allows the higher-orderone packet to shift to the second data holding step, allows thelower-order three packets of the first, second and third data to shiftto a transmit control step as the fourth, fifth and sixth data; andwhen, upon completion of the steps, data corresponding to three packetshas been stored in the second data holding step, switches steps to shiftto the transmit control step with the data being used as the seventhdata constituted by the fourth, eighth and twelfth packets; and transmitcontrol means which successively transmits the fourth, fifth, sixth andseventh data that have been shifted from the data selection step to abuffer memory area.
 12. A data transmission apparatus, which processesdata through an N-bit bus, comprising: means which reads M-bit formatdata, which is a basic data unit for data processing, from a buffermemory; and means which converts the M-bit format data thus read toN-bit format data, which is a basic data unit for data transmission,wherein with respect to the conversion system from the M-bit format datato the N-bit format data, first data constituted by first, second andthird packets, second data constituted by fourth, fifth and sixthpackets, third data constituted by seventh, eighth and ninth packets,and fourth data constituted by tenth, eleventh and twelfth packets areinputted, the apparatus comprising: transmit control means whichsuccessively transmits the first, second, third and fourth data to dataselection means; data selection means which receives data from thetransmit control means, and when the first data is inputted, outputs thedata to second data holding means, while, when the second, third andfourth data are inputted, respectively adds the first, second and thirdpackets held at the second data holding means to the higher-orderpackets thereof to form fifth, sixth and seventh data, and outputs thefifth, sixth and seventh data to first data holding means; first dataholding means which receives and holds the fifth, sixth and seventh dataoutputted from the data selection means; and second data holding meanswhich receives and holds the first data outputted from the dataselection means.